TW202206715A - Motion guide device - Google Patents

Abstract

The subject of the present invention is to provide a motion guide device which is able to prevent a ball from touching the edge of a ball rolling groove of a track member when the ball is transferred from the rolling surface of the inner peripheral side (inner peripheral side part) of a direction change path to a track member. The solution of the present invention is that a motion guide device comprises: a rail member (2) having a ball rolling groove (2a); and a moving member being relatively movably assembled to the rail member (2). The moving member comprises: a moving member body having a load ball rolling groove facing the ball rolling groove (2a) and a return path substantially parallel to the load ball rolling groove; and a cover member having a direction change path. In the cross-sectional view of the motion guide device perpendicular to the length direction of the track member (2), R＞r is defined when the radius of curvature of the ball rolling groove (2a) is defined as R and the distance from the center of the ball (O) to the rolling surface (21) of the inner circumference side (inner circumference side part (9a)) of the direction change path is defined as r.

Description

motion guide

The present invention relates to a motion guide device for guiding the motion of movable bodies such as a workbench.

There is known a motion guide device (for example, refer to Patent Document 1) that guides the motion (linear motion or curvilinear motion) of a movable body such as a table. A motion guide device includes a rail member and a moving member assembled to the rail member so as to be relatively movable. A movable body such as a work table is attached to the moving member. Between the track member and the moving member, there are a plurality of rolling balls. Using the rolling motion of the balls, the movable body can be guided with high precision and high rigidity by guiding the motion of the movable body.

A ball rolling groove is formed on the track member. The moving member includes a moving member body and a cover member. On the main body of the moving member, a loaded ball rolling groove opposite to the ball rolling groove and a return path substantially parallel to the loaded ball rolling groove are formed. A direction changing channel is formed on the cover member, and the direction changing channel is connected to the load channel and the return channel between the ball rolling groove and the load ball rolling groove. The cover member includes a cover body on which the outer peripheral side of the direction changing passage is formed, and an inner peripheral side part on which the inner peripheral side of the direction changing passage is formed. The circulation path is composed of a load track, a return track and a direction change track. Arrange a plurality of balls in the circulation path. When the moving body moves relative to the track member, the plurality of balls circulate in the circulation path. [Prior Art Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2004-68880

(The problem that the invention intends to solve)

However, the previous motion guide device belongs to a type of balls that come into contact with the edge of the ball rolling groove of the track member when the balls move from the rolling surface on the inner peripheral side (inner peripheral side part) of the direction changing channel to the track member. structure. Therefore, although it usually does not cause a problem, when the motion guide device is used in the high-speed area, high stress will be generated at the contact portion between the ball and the edge of the ball rolling groove, which may cause indentation at the contact portion.

Therefore, the object of the present invention is to provide a motion guide device that can prevent the balls from contacting the edges of the ball rolling grooves of the track member when the balls move from the rolling surface on the inner peripheral side of the direction changing channel to the track member. (Technical means to solve problems)

In order to solve the above-mentioned problems, one aspect of the present invention is to provide a motion guide device including: a track member having ball rolling grooves; The moving member includes: a moving member body having a load ball rolling groove facing the ball rolling groove, and a return path substantially parallel to the load ball rolling groove; and a cover member having a direction change path; the direction change path The load track and the return track are connected between the ball rolling groove and the loaded ball rolling groove, and a plurality of balls are arranged in a row on a circulation path formed by the load track, the return track and the direction changing track; it is characterized in that : In the cross-sectional view of the motion guide device perpendicular to the longitudinal direction of the track member, when the radius of curvature of the ball rolling groove is set as R, and the distance from the center of the ball to the inner peripheral side of the direction changing channel is When the distance to the rolling surface is set to r, R>r is set. (Compared to the efficacy of the prior art)

According to the present invention, since the rolling surfaces are arranged inside the extension lines of the ball rolling grooves, when the balls move from the rolling surfaces to the track members, the balls can be prevented from contacting the edges of the ball rolling grooves of the track members.

Hereinafter, the motion guiding device according to the embodiment of the present invention will be described with reference to the accompanying drawings. However, the motion guide device of the present invention can be embodied in various forms, and is not limited to the embodiments described in this specification. This embodiment is provided for the purpose of enabling those skilled in the art to fully understand the technical scope of the present invention by being fully disclosed in the specification.

FIG. 1 is an external perspective view (including a partial cross-sectional view) of a motion guiding device 1 according to an embodiment of the present invention. Furthermore, in the following description, for the convenience of description, the motion guide device 1 is arranged on a horizontal plane, and the direction when the motion guide device 1 is viewed from the front, that is, up and down, left and right, and front and rear in FIG. The configuration of the guide device 1 will be described. Of course, the configuration of the motion guiding device 1 is not limited to this.

As shown in FIG. 1 , the motion guide device 1 includes a rail 2 as a rail member, and a block 3 as a moving member assembled to the rail 2 so as to be relatively movable. The movement of the block body 3 relative to the rail 2 is relative movement, which can move the block body 3 or the rail 2 as well.

The track 2 extends linearly. On the upper surface of the rail 2, there are formed through holes 2b for bolts for mounting the rail 2 on the base. On the left and right sides of the track 2, four ball rolling grooves 2a extending along the longitudinal direction of the track 2 are formed. In the present embodiment, a pair of protrusions 20 protruding in the left-right direction is formed on the upper portion of the rail 2 , and two ball rolling grooves 2 a are formed above and below each protrusion 20 . The cross-sectional shape of the ball rolling groove 2a is a circular arc or a Gothic arch. Furthermore, the rail 2 may extend in a curved shape. The number and arrangement of the ball rolling grooves 2 a can be appropriately changed according to the application of the motion guide device 1 .

When viewed from the front, the block 3 is in the shape of an inverted U, and is assembled across the track 2 . The block 3 includes: a block body 4 serving as a moving member body; and a pair of cover members 5 a and 5 b attached to both end surfaces of the block body 4 in the moving direction. On the block body 4, a load ball rolling groove 4a is formed opposite to the ball rolling groove 2a of the track 2, and a return path 12 is formed parallel to the load ball rolling groove 4a. The cross-sectional shape of the loaded ball rolling groove 4a is a circular arc or a Gothic arch. Element number 4c is a screw hole for attaching a movable body such as a workbench to the block body 4, and 6a and 6b are sealing members.

FIG. 2 is a cross-sectional view showing a circulation path. The circulation path is composed of a load track 11 , a return track 12 , and a U-shaped direction change track 13 connected to the load track 11 and the return track 12 . A plurality of balls 7 are arranged in a line in the circulation path. When the block 3 moves relatively with respect to the track 2, the balls 7 circulate within the circulation path. A load track 11 is formed between the ball rolling groove 2a and the load ball rolling groove 4a. In the load track 11 , the balls 7 are in a loaded state, and are subjected to a preload, a load of a movable body, and the like. The return channel 12 is formed in the block body 4 . The direction changing path 13 is formed in the cover members 5a and 5b. The inner diameter of the return channel 12 and the direction conversion channel 13 is slightly larger than the diameter of the ball 7 . In the return path 12 and the direction change path 13, the balls 7 are in an unloaded state.

3 and 4 are perspective views showing the cover member 5a viewed from the block body 4 side. In FIGS. 3 and 4 , the direction of viewing the cover member 5 a is changed for easy understanding. As shown in FIG. 3, four direction changing paths 13 are formed on the cover member 5a. Element number 13 a is one end of the direction changing track 13 connected to the load track 11 , and 13 b is the other end of the direction changing track 13 that is connected to the return track 12 . The cover member 5a and the cover member 5b (see FIG. 1 ) have the same shape.

The cover member 5a includes a cover body 8 on which the outer peripheral side of the direction changing passage 13 is formed, and inner peripheral side parts 9a and 9b on which the inner peripheral side of the direction changing passage 13 is formed. Like the block body 4 of the block body 3, when viewed from the front, the cover body 8 is in an inverted U-shape. The inner peripheral side parts 9a and 9b are fitted into the recessed parts of the left and right sleeve parts 8-1 of the cover body 8. As shown in FIG.

FIG. 5 is a perspective view showing the inner peripheral side part 9a. The inner peripheral side of the upper and lower two direction changing passages 13 is formed on the inner peripheral side member 9a. The inner peripheral side of the direction changing channel 13 is formed in an arc-shaped cross section, and is formed in an inverted U-shape as a whole. On the end 13a on the load track 11 side of the upper direction changing track 13, and at a portion close to the ball rolling groove 2a (see Fig. 3(b) ), a flat rolling surface 21 is formed. The inner peripheral side member 9a is vertically symmetrical. A rolling surface 21 is also formed at the end portion 13a of the lower direction changing track 13 on the load track 11 side. The inner peripheral side member 9a and the inner peripheral side member 9b (refer to Fig. 3(a) ) are bilaterally symmetrical. The inner peripheral side member 9b also has the same rolling surface 21 as the inner peripheral side member 9a.

Fig. 3(b) is an enlarged view of part b of Fig. 3(a). Component number 2 is a track, 2a is a ball rolling groove, 8 is a cover body, 9a is an inner peripheral side part, and 21 is a rolling surface. When the balls 7 enter the load path 11 from the direction changing path 13, the balls 7 move from the rolling surface 21 of the inner peripheral side member 9a to the ball rolling grooves 2a of the track 2. On the other hand, when the balls 7 enter the direction changing path 13 from the load path 11, the balls 7 come into contact with the contact portion 8a (see also FIG. 4) of the cover body 8, and are guided to the rolling surface by the contact portion 8a. On the side 21 , it is transferred from the ball rolling groove 2 a to the rolling surface 21 . Furthermore, a wedge-shaped scooping portion may be provided on the cover body 8 within the width of the ball rolling groove 2a, and the balls 7 may be scooped up by the scooping portion.

Element number 22 is the edge of the ball rolling groove 2a. The ball rolling groove 2a is formed as a concave curved surface with a circular arc cross-section up to the edge 22 thereof. A convex curved surface 23 having an arc-shaped cross section continuous with the edge 22 is formed on the outer side of the edge 22 (the lower side in FIG. 3( b )). An inclined surface 24 is formed on the outer side of the convex curved surface 23 (the lower side in FIG. 3( b )).

FIG. 6 is a diagram showing contact angles L1 and L2 of the motion guide device 1 (a cross-sectional view of the rail 2 and the block body 4 ). The contact angle lines L1 and L2 show the direction in which the motion guiding device 1 can bear the load. The contact angles δ1 and δ2 are the angles between the contact angle lines L1 and L2 and the horizontal line H. The contact angles δ1 and δ2 can be appropriately changed according to the application of the motion guide device 1 . Furthermore, the direction of the direction changing lane 13 is different from the directions of the contact angle lines L1 and L2. This is to reduce the size of the block body 4 in the up-down direction. The directions of the contact angle lines L1 and L2 may also be aligned with the direction of the direction changing channel 13 .

7 is a cross-sectional view showing the motion guide device 1 perpendicular to the length direction of the rail 2 (a cross-sectional view of the motion guide device 1 at the boundary X (refer to FIG. 2 ) of the block body 4 and the cover member 5a). Element number 2 is a track, 2a is a ball rolling groove, 9a is an inner peripheral side part, and 21 is a rolling surface.

When the radius of curvature of the ball rolling groove 2a is set to R, and the distance from the ball center O to the rolling surface 21 of the inner peripheral side member 9a is set to r, R>r is set. Wherein, R>r means that the rolling surface 21 exists on the inner side of the extension line 2a1 of the ball rolling groove 2a. This is so that the balls do not come into contact with the edge 22 of the ball rolling groove 2a.

FIG. 8( a ) shows the aspect where R>r is set in this embodiment, and FIG. 8( b ) shows the prior art where R<r is set. As shown in FIG. 8( b ), in the prior art, since R<r is set, the rolling surface 21 exists on the outer side of the extension line 2 a 1 of the ball rolling groove 2 a (the lower side in FIG. 8( b ) ). Therefore, when the balls 7 travel from the rolling surface 21 to the ball rolling grooves 2a, the balls 7 will contact the edges 22 of the ball rolling grooves 2a. At this time, the ball 7 is supported by the contact point 31 and the edge 22 of the rolling surface 21 . On the other hand, as shown in FIG. 8( a ), in the present embodiment, since R>r is set, the rolling surface 21 exists on the inner side of the extension line 2a1 of the ball rolling groove 2a. Here, the rolling surface 21 existing on the inner side is shown with oblique lines. When the ball 7 moves from the rolling surface 21 to the ball rolling groove 2a, since the ball 7 is supported by the contact point 31 on the rolling surface 21 and the contact point 32 on the ball rolling groove 2a, it can be prevented from contacting the ball rolling groove 2a. contact with the edge 22.

Furthermore, as shown in FIG. 7 , the center O of the ball is the center O of the ball 7 in the no-load state in contact with the ball rolling groove 2a, and is located on the contact angle line L1. Since the curvature radius R of the ball rolling groove 2a is usually set to be 51% to 53% of the diameter of the ball 7, the curvature center C of the ball rolling groove 2a is slightly offset from the ball center O. Figure 7 magnifies this deviation.

Like FIG. 7 , FIG. 9 shows a cross-sectional view of the motion guide device 1 perpendicular to the length direction of the rail 2 . Among them, 2 is a track, 2a is a ball rolling groove, 9a is an inner peripheral part, and 21 is a rolling surface.

Under the above condition of R>r, when the angle between the straight line L3 connecting the center of curvature C of the ball rolling groove 2a and the edge 22 of the ball rolling groove 2a and the vertical line V is set as γ, and the inner peripheral side parts When the angle between the rolling surface 21 of 9a and the horizontal line H is set to θ, it is set to be θ>γ. This is to ensure the clearance between the ball 7 and the rolling surface 21 at the nominal position. The inner peripheral side part 9a is usually a resin molded product, and a dimensional error inevitably occurs. By setting θ>γ, the dimensional error of the inner peripheral side part 9a can be tolerated by securing the clearance.

This point is described in detail below. FIG. 9 shows a state in which the balls 7 are in contact with the ball rolling grooves 2a and move from the nominal position to the vicinity of the edge 22 of the ball rolling grooves 2a. The nominal position is the position when the ball center O is located on the contact angle line L1 (refer to FIG. 7 ). As shown in FIG. 9 , when R>r is set, the ball 7 contacts the rolling surface 21 before the ball 7 moves from the nominal position to the edge 22 of the ball rolling groove 2 a (right side in FIG. 9 ). Conversely, when the balls 7 start from the front side of the edge 22 of the ball rolling groove 2a and move to the nominal position (left side in FIG. 9 ), a gap is generated between the balls 7 and the rolling surface 21 . If θ>γ is set, and the purpose of increasing the angle θ can be used to ensure the clearance.

On the other hand, when θ<γ (the rolling surface 21 is made horizontal or nearly horizontal), even if the ball 7 starts from the front side of the edge 22 of the ball rolling groove 2a and moves to the nominal position (the left side in FIG. 9 ), Also, the clearance between the balls 7 and the rolling surfaces 21 cannot be ensured. When the rolling surface 21 is made horizontal or nearly horizontal, since the rolling surface 21 exists near the lowest point of the ball 7, even if the ball 7 moves to the left in FIG. 9, the clearance remains substantially unchanged. In this case, if a dimensional error occurs in the inner peripheral side part 9a, the balls 7 and the rolling surfaces 21 interfere with each other, and there is a possibility that the balls 7 cannot be circulated.

The configuration of the present embodiment has been described above. However, the present invention is not limited to the present embodiment, and can be embodied in other embodiments within the scope of not changing the essential content of the present invention. For example, in this embodiment, the inner peripheral side of the direction changing channel is formed on the inner peripheral side part, but it may be formed in the cover body.

This specification is based on Japanese Patent Application No. 2020-087900 filed on May 20, 2020. Its contents are all included in this manual.

1: Motion guide device 2: Track (track member) 2a: Ball rolling groove 2a1: extension cord 2b: Through hole 3: Block (moving member) 4: Block body (moving member body) 4a: Loaded ball rolling groove 4c: screw hole 5a, 5b: Cover member 6a, 6b: sealing member 7: Ball 8: Cover body 8a: Contact part 8-1: Sleeves 9a, 9b: Inner peripheral side parts (inner peripheral side of the direction change channel) 11: Load channel 12: Return Road 13: Direction change road 13a: one end 13b: the other end 20: Protrusions 21: Rolling Surface 22: The edge of the ball rolling groove 23: Convex Surface 24: Inclined surface 31: Touchpoints C: The center of curvature of the ball rolling groove H: horizontal line L1, L2: contact angle line L3: A straight line connecting the center of curvature of the ball rolling groove and the edge of the ball rolling groove O: Ball Center V: plumb line

FIG. 1 is an external perspective view (including a partial cross-sectional view) of a motion guiding device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the circulation path of the motion guide device of the present embodiment. 3 is a perspective view of a cover member of the motion guide device of the present embodiment ( FIG. 3( a ) is a perspective view of the cover member, and FIG. 3( b ) is an enlarged view of part b of FIG. 3( a ). FIG. 4 is a perspective view of the cover member of the motion guide device of the present embodiment (viewed in a different direction from FIG. 3 ). Fig. 5 is a perspective view of the inner peripheral side parts of the motion guide device of this embodiment. FIG. 6 is a diagram showing the contact angle of the motion guide device of the present embodiment. FIG. 7 is a cross-sectional view of the motion guide device of the present embodiment perpendicular to the longitudinal direction of the rail. FIG. 8 is a cross-sectional view perpendicular to the longitudinal direction of the motion guide device and the track (FIG. 8(a) shows the present embodiment, and FIG. 8(b) shows the prior art). FIG. 9 is a cross-sectional view of the motion guide device of this embodiment perpendicular to the longitudinal direction of the rail.

2: Track (track member)

2a: Ball rolling groove

2a1: extension cord

9a: Inner peripheral side parts

21: Rolling Surface

22: The edge of the ball rolling groove

C: The center of curvature of the ball rolling groove

L1: Contact angle line

O: Ball Center

Claims (3)

A motion guiding device is provided with: a track member having ball rolling grooves; and a moving member, which is relatively movable assembled to the aforementioned rail member, and The aforementioned moving components include: a moving member body having: a load ball rolling groove facing the ball rolling groove; and a return path substantially parallel to the load ball rolling groove; and a cover member having a direction change path connected to the load path and the return path between the ball rolling groove and the load ball rolling groove, and A plurality of balls are arranged in an array on the circulation path formed by the load path, the return path and the direction change path; It is characterized by: In a cross-sectional view of the motion guide device perpendicular to the length direction of the track member, When the radius of curvature of the ball rolling groove is R, and the distance from the center of the ball to the rolling surface on the inner peripheral side of the direction changing path is r, R>r is set. The motion guide device according to claim 1, wherein the angle between the straight line connecting the center of curvature of the ball rolling groove and the edge of the ball rolling groove and the vertical line is set as γ, and the angle between the rolling surface and the horizontal line is set as γ. When the angle of the clip is set to θ, it is set to be θ>γ. The motion guide device according to claim 1 or 2, wherein the cover member comprises: a cover body on which the outer peripheral side of the direction changing channel is formed; and an inner peripheral side part on which the inner peripheral side of the direction changing channel is formed ;and On the inner peripheral side part, the rolling surface on the inner peripheral side of the direction changing channel is formed.

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